| 摘要 |
PURPOSE:To speedily extract and displays road information that a person on the vehicle requires from a road map data base by extracting road information in road kind units according to set display priority order. CONSTITUTION:Road map data on an area to be displayed which is set with input keys is read in a D-RAM 22 from a CD-ROM 16. The road map data stored in the D-RAM 22 are retrieved to extract object roads to be displayed according to the set display priority order and visibility evaluation criteria. The respective data on the extracted object roads to be displayed are converted from an earth coordinate system to the coordinate system of a display screen and developed as bit map data in a V-RAM 20, and a mark indicating the current position of the vehicle and the names of places, etc., are superimposed on the road map. Further, the bit map data in the V-RAM 20 are transferred to a CRT 18 through a graphic controller 19 to display the road map based upon the set display priority order and visibility evaluation criteria on the CRT 18. |
